Thanks to her lengthy tenure – Google's office was once her garage – and her success running Google's massive ads business, Wojcicki is one of Google CEO Larry Page's most trusted confidantes.

So much so, that there is a saying at Google: "What Susan wants, Susan gets."

According to a report in The Information, she told Page she wanted to be a CEO, and would leave Google to become one if she had to. So she got the YouTube job.

But what about Shishir Mehrotra?

Mehrotra is YouTube's vice president of product. According to LinkedIn, he is "responsible for YouTube product, engineering, and user experience teams including consumer, content creator, and monetization functions."

For some months now, it's been out there YouTube CEO Salar Kamangar has been looking to exit that job for a new challenge at Google. Many said that Kamangar, himself a longtime Googler and Page confidante, had already returned to the mothership, and was mostly focused on advising Page.

Kamangar's presumed successor was always his top lieutenant at YouTube, Mehrotra.

In fact, the word from many Googlers was that Mehrotra was already essentially running YouTube.

Obviously, he won't be any longer. Wojcicki wanted that job. She got it.

One of Wojcicki's first big challenges will be making sure the guy who didn't sticks around.